Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Department of Endocrinology and Metabolism, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul, Korea.
Endocrinol Metab (Seoul). 2024 Aug;39(4):615-621. doi: 10.3803/EnM.2023.1896. Epub 2024 Aug 7.
The adequate dose of levothyroxine (LT4) for patients who have undergone total thyroidectomy (TT) for differentiated thyroid cancer (DTC) is uncertain. We evaluated the LT4 dose required to achieve mild thyroid-stimulating hormone (TSH) suppression in DTC patients after TT.
The electronic medical records of patients who underwent TT for DTC and received mild TSH suppression therapy were reviewed. Linear regression analysis was performed to evaluate the association between LT4 dose (μg/kg) and an ordinal group divided by body mass index (BMI). We also evaluated the trend in LT4 doses among groups divided by BMI and age.
In total, 123 patients achieved mild TSH suppression (0.1 to 0.5 mIU/L). The BMI variable was divided into three categories: <23 kg/m2 (n=46), ≥23 and <25 kg/m2 (n=30), and ≥25 kg/m2 (n=47). In the linear regression analysis, BMI was negatively associated with the LT4 dose after adjusting for age and sex (P<0.001). The LT4 doses required to achieve mild TSH suppression based on the BMI categories were 1.86, 1.71, and 1.71 μg/kg, respectively (P for trend <0.001). Further analysis with groups divided by age and BMI revealed that a higher BMI was related to a lower LT4 dose, especially in younger patients aged 20 to 39 (P for trend=0.011).
The study results suggest an appropriate LT4 dose for mild TSH suppression after TT based on body weight in patients with DTC. Considering body weight, BMI, and age in estimating LT4 doses might help to achieve the target TSH level promptly.
甲状腺全切术（TT）后分化型甲状腺癌（DTC）患者左甲状腺素（LT4）的适宜剂量仍不明确。我们评估了 DTC 患者 TT 后达到轻度甲状腺刺激激素（TSH）抑制所需的 LT4 剂量。
回顾性分析了行 TT 治疗 DTC 并接受轻度 TSH 抑制治疗的患者的电子病历。采用线性回归分析评估 LT4 剂量（μg/kg）与按体重指数（BMI）划分的有序分组之间的关系。我们还评估了按 BMI 和年龄分组的 LT4 剂量趋势。
共有 123 例患者实现了轻度 TSH 抑制（0.1 至 0.5 mIU/L）。BMI 变量分为三组：<23 kg/m2（n=46），≥23 且<25 kg/m2（n=30），≥25 kg/m2（n=47）。在调整年龄和性别后，线性回归分析显示 BMI 与 LT4 剂量呈负相关（P<0.001）。根据 BMI 类别，达到轻度 TSH 抑制所需的 LT4 剂量分别为 1.86、1.71 和 1.71 μg/kg（P 趋势<0.001）。进一步分析年龄和 BMI 分组显示，较高的 BMI 与较低的 LT4 剂量相关，尤其是在 20 至 39 岁的年轻患者中（P 趋势=0.011）。
本研究结果提示 DTC 患者 TT 后根据体重制定 LT4 轻度 TSH 抑制的适宜剂量。考虑体重、BMI 和年龄来估计 LT4 剂量可能有助于快速达到目标 TSH 水平。
